Process for the preparation of hydroxybenzyl esters of cyanuric acid

ABSTRACT

Hydroxybenzyl-substituted isocyanurates are prepared by the condensation reaction of a phenol with cyanuric acid or a partial ester of cyanuric acid and formaldehyde. The hydroxybenzylsubstituted isocyanurates and particularly 3,5-dialkyl-4hydroxybenzyl isocyanurates and useful stabilizers for a wide variety of organic materials including olefin homopolymers and copolymers.

United States Patent Gilles 1 June 13, 1972 [s41 PROCESS FOR THEPREPARATION OF 2,454,078 11/1948 McGrew ..260/249.6

HYDROXYBENZYL EsTERs OF OTHER PUBLICATIONS CYANURIC ACID [72] Inventor:Jack C. Gilles, Shaker Heights, Ohio [73] Assignee: The B. F. GoodrichCompany, New York,

[22] Filed: May 27, 1969 [21] App]. No.: 828,376

[52] U.S. Cl .260/248 NS, 260/458 N, 260/949 GC [51 Int. Cl. ..C07d55/38 5 8] Field of Search 260/248 NS, 249.6

[56] References Cited UNITED STATES PATENTS 3,531,483 9/1970 Gilles..260/248 Cyanuric Acid," F.M.C. Corporation Product Bulletin 108, April1965, New York, pp. l- 7 and 13- 22.

Primary E.\'aminer.|ohn M. Ford Attorney-J. Hughes Powell, Jr. andErnest K. Bean [57] ABSTRACT l-lydroxybenzyl-substituted isocyanuratesare prepared by the condensation reaction of a phenol with cyanuric acidor a partial ester of cyanuric acid and formaldehyde. The hydroxybenzyl-substituted isocyanurates and particularly 3,5-dialkyl-4-hydroxybenzyl isocyanurates and useful stabilizers for a wide varietyof organic materials including olefin homopolymers and copolymers.

20 Claims, No Drawings PROCESS FOR THE PREPARATION OF HYDROXYBENZYLESTERS OF CYANURIC ACID BACKGROUND OF THE INVENTION Esters of cyanuricacid wherein the ester substituent is an aliphatic hydrocarbon radicalare known. These alkyl-substituted isocyanurates have been prepared byreacting alkyl halides and potassium cyanate and other suchtrimerizations of cyanates and isocyanates; reacting cyanuric acid withan alkyl halide or alkenyl halide in the presence of a basic acceptor;or the reaction of a metal salt of cyanuric acid with an alkyl sulfateor alkyl halide. Processes available for the preparation ofaryl-substituted isocyanurates, especially were the aryl substituentcontains a functional group such as a hydroxyl group, are even morelimited. These processes typically result in poor yields of a low purityproduct due to the numerous side reactions which occur and require longreaction times and the use of costly starting materials.

SUMMARY OF THE INVENTION We have now discovered, quite unexpectedly, aprocess whereby hydroxybenzyl-substituted isocyanurates are obtained ingood yield and high purity. The present invention provides a simple andeconomical process for preparing hydroxybenzyl-substituted isocyanuratesby the condensation reaction of a phenol and cyanuric acid or partialester of cyanuric acid with formaldehyde at an elevated temperature. Thereaction is preferably conducted in an organic reaction medium and inthe presence of a basic catalyst. The isocyanurate ring may besubstituted with one, two or three hydroxybenzyl groups depending on themolar proportion of phenol employed and the number of reaction sitesN-H) available on the ring. The phenols employed contain one or morealkyl radicals on the aromatic nucleus, and more preferably are 2,6-dialkyl phenols wherein the alkyl groups are tertiary alkyl groups. Theprocess is generally conducted in the temperature range between about 70and 180 C. Basic materials present in catalytic amounts are useful forthe present process and insure high yields in very short reaction times.The preferred basic catalysts are monoand polyarnines, alcoholates andhydroxides.

The hydroxybenzyl-substituted isocyanurates obtained by the presentprocess are useful stabilizers for a wide variety of organic materials.They possess low volatility, are non-staining and are extremelyeffective protective agents for organic polymeric materials, bothnatural and synthetic, which are subject to the deleterious effects ofoxygen, heat and both visible and ultraviolet light. They are especiallyuseful as stabilizers for a-olefin homopolymers and copolymers,particularly, polyethylene, polypropylene, ethylene-propylene copolymersand ethylene-propylene terpolymers.

DETAILED DESCRIPTION The present invention is directed to thepreparation of hydroxybenzyl-substituted isocyanurates, and moreparticularly, to a process for the preparation of isocyanuratessubstituted with one or more hindered phenol groups. The processconsists of the condensation of a phenol, cyanuric acid or a partialester of cyanuric acid and formaldehyde at an elevated temperature. Itis particularly useful for the reaction of 2,6-dialkyl phenols,formaldehyde and cyanuric acid to obtain 3,5-dialkyl-4-hydroxybenzylisocyanurates. When cyanuric acid is employed, the amount of the phenolcan be varied so as to vary the degree of substitution on theisocyanurate ring. Reaction of a partial ester of cyanuric acid withphenol and formaldehyde in accordance with the present process willyield a mixed ester of cyanuric acid, that is, isocyanurates containingone or two other substituents besides the hydroxybenzyl group.

Cyanuric acid and partial esters of cyanuric acid corresponding to thestructural formula lt1N N-ll wherein R is a branched or straight chainaliphatic hydrocarbon radical containing from one to carbon atoms and R,is hydrogen or a branched or straight chain aliphatic hydrocarbonradical containing from one to 20 carbon atoms, are employed for theprocess. Especially useful partial esters are those containing one ortwo alkyl groups containing from six 20 to 78 carbon atoms such ashexyl, 2-ethylhexyl, octyl, decyl, lauryl, palmityl and stearyl. For theprocess it is essential when a cyanuric acid ester (isocyanurate) is tobe reacted that there be at least one NI-I grouping available on thering to provide the necessary reaction site for the condensation withthe phenol and formaldehyde. Although it is not essential that all threenitrogen atoms of the cyanuric acid ring have available hydrogen,excellent results have been obtained where cyanuric acid is employed togive tris(4-hydroxybenzyl)isocyanurates. Other structurally relatedheterocyclic compounds, that is, those having a 0 l I 0 II I ll -CN-Cmolecular grouping in the ring, can similarly be reacted with phenol andformaldehyde to achieve hydroxybenzyl substitution in accordance withthe present invention. Such compounds include: uric acid, hydantoin,allantoin, parabanic acid, alloxan, uracil, thymine, barbituric acid,phenobarbitone and the like.

Reacted with the cyanuric acid or partial ester of cyanuric acid is aphenol, or mixture of phenols, corresponding to the formula wherein R isan alkyl group, either aliphatic or cycloaliphatic, containing from oneto 18 carbon atoms and R R R and R are hydrogen or an alkyl group,either aliphatic or cycloaliphatic containing from one to 18 carbonatoms but at least one of the R R R or R groups is a hydrogen. Morepreferably the phenol is a 2,6-dialkyl phenol where R and R are alkylgroups containing from one to 12 carbon atoms and R is hydrogen.Excellent results have been obtained when R and R are tertiary alkylgroups containing from four to eight carbon atoms and R.,, R:, and R arehydrogen. Illustrative of the alkyl groups which may be substituted onthe phenol ring are methyl, ethyl, n-propyl, isopropyl, butyl, hexyl,cyclohexyl, methylcyclohexyl, 2-ethylhexyl, octyl, lauryl, and the like.Exemplary tertiary alkyl groups are t-butyl, t-amyl,l-methyll-ethylpropyl, l,l -diethylbutyl, l,1,2,2-tetramethylpropyl, 1l-dimethylpentyl, l,l,2-tr1'methylpentyl and the like.

In addition to the phenol and the cyanuric acid or partial esterthereof, formaldehyde is employed in the present 70 process. Any reagentwhich will serve as a source of formaldehyde such as formalin solutions,paraformaldehyde and trioxane are suitable for the process and when theterm formaldehyde appears subsequently in the specification and claimsit is intended to include formalin, paraformaldehyde, trioxane and allother formaldehyde-liberating compounds.

Excellent results have been obtained when the source of formaldehyde isparaformaldehyde, typically having up to about 100 or more formaldehydeunits polymerized together. These materials are readily depolymerizedunder the reaction conditions employed and serve as a convenient andeconomical source of formaldehyde.

The reaction may be conducted with or without a catalyst. If a catalystis employed, organic and inorganic basic materials such as primary,secondary and tertiary monoamines and polyamines, alkali metalalcoholates, alkali metal hydroxides, quaternary ammonium hydroxides andthe like, will be used. The usual basic catalysts include diethylarnine,tributylarnine, ethylenediamine, tetramethylenediamine,hexamethylenetetraamine, sodium ethoxide, potassium ethoxide, potassiumt-butoxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide,tetrarnethylammonium hydroxide, trimethylbenzylammonium hydroxide,tricaprylylmethylammonium hydroxide and the like. Excellent results havebeen obtained when polyamines, preferably having a polycyclic structuresuch as hexamethylenetetraamine, are employed. The amount of catalystused can range up to about 0.1 mol per mol cyanuric acid or partialester thereof and more preferably will be between about 0.000] and 0.02mol per mol cyanuric acid.

The reaction can be conducted in an organic diluent which may also serveas a solvent for the cyanuric acid or partial ester and/or the phenol.The reaction product may also be soluble in the organic reaction mediumor it may be ad vantageous to the recovery that the product be insolubleor have limited solubility. Besides solvent capacity another criterionfor choosing the organic reaction diluent is the boiling point of thematerial. The boiling point of the diluent will usually be high enoughto permit reaction within the preferred temperature range, that is,above about 70 C. Excellent results can be obtained, however, withdiluents which have boiling points as low as 50 C. if the reaction isconducted in a pressure vessel. In some instances it may even beadvantageous to employ low boiling diluents to facilitate recovery ofthe reaction product by steam stripping or the like. Especially usefuldiluents for the present process include amides such as formamide andacetamide, N-alkyl-substituted amides such as N-ethylformamide,N,N-dimethylformamide, N ,N-diethylformamide, N,N-dimethylacetamide andthe like; dimethyl sulfoxide; acetonitrile; propylene carbonate; N-methyl-Z-pyrrolidone and the like. In general, organic solvents havingsolubility parameters (5) above about as defined in lnterchemicalReview, 14, 3-16, 31-46 (1955) are useful diluents for the presentprocess.

It is not necessary that the reaction be conducted under anhydrousconditions. Water may be present in the reaction medium withoutinterfering with the yield of the product obtained and the productpurity. Due to the ready solubility of formaldehyde in water, an amountof water will even be advantageous to maintain the formaldehyde in thereaction system. Other advantages may also be realized due to thepresence of water in the reaction system. For example, if sufficientwater is present the product, immediately upon formation, willprecipitate from solution leaving only the reactants. Such precipitationof the product is advantageous in a continuous system for continuousremoval of the reaction product from the reaction zone. Excellent yieldsof high purity product have been obtained when the reaction mediumcontains up to 40% by weight water, however, best results are obtainedwhen less than about 25% by weight water is employed.

It is usual to conduct the reaction at a temperature greater than about70 C. When temperatures below about 50 C. are employed the reaction ratedrops off markedly and lower yields of the product are obtained.Temperatures up to about l80 C. may be employed, however, best resultsare obtained in the temperature range between about 90 and 150 C. Thereaction will be conducted at atmospheric, sub-atmospheric orsuper-atmospheric pressures depending on the reaction temperature andthe particular reaction medium employed.

When low-boiling diluents are used closed reactors are employed andoperating pressures up to about psig will typically be developed. Thereaction can be conducted at pressures up to about 500 psig with noadverse results.

Although the process is readily carried out by combining the individualreactants in the manner and proportions described above, alternativetechniques may also be employed to give similar results. For example,formaldehyde hydrate may be formed and reacted with the phenol andcyanuric acid or ester of cyanuric acid or the methylol derivative ofcyanuric acid or partial ester of cyanuric acid can be pre-formed andsubsequently reacted with the phenol to give thehydroxybenzyl-substituted isocyanurates. Such a process as the lattermay be desirable and facilitate conducting the process on a continuousbasis since the methylol derivative could be formed first and then in asubsequent stage react with the phenol.

For the success of the present process all that is required is that thereactants be present within the defined molar quantities to achieve thedesired degree of substitution and that the reaction be conducted inaccordance with the abovedescribed reaction conditions. The molar ratioof the reactants employed will vary depending on the number of availablereaction sites NH), that is, whether cyanuric acid or a partial ester ofcyanuric acid is employed, and the degree of reaction desired. Forexample, if cyanuric acid is employed 3 mols of the phenol will bereacted per mol of the cyanuric acid for complete reaction to give thetris(hydroxybenzyl)isocyanurate. With a partial ester of cyanuric acidcontaining two reactive Nl-l sites, such as hexylisocyanurate, 2 mols ofthe phenol will be reacted. If all the sites are to be reacted a molarexcess of the phenol may be used to insure completeness of the reaction.The use of excess phenol will also compensate for impurities which maybe present in the reaction system and also insure a rapid reaction rate.In general, no particular advantage is realized when more than about 20%excess of the phenol is present. Excellent results have been obtainedwhen 5% molar excess of the phenol is employed. Where less than completesubstitution of the cyanuric acid or partial ester is required, themolar amount of phenol will be decreased accordingly from the optimumlevel employed to react one phenol group per N-H group. For example, ifhexylisocyanurate is to be reacted and it is desired that only onehydroxybenzyl group be substituted thereon, one mol of the phenol isemployed per mol hexyl isocyanurate.

Just as with the phenol, the amount of formaldehyde required for thereaction is dependent on the number of available N-H reaction sites andthe degree of substitution desired. Equimolar amounts of the phenol andformaldehyde or a slight molar excess of formaldehyde, up to about 20%,based on the phenol will generally be used. With 5 to 10% molar excessof the formaldehyde based on the phenol, excellent yields of high purityhydroxybenzyl-substituted isocyanurates are obtained.

The following examples will illustrate the invention more fully,however, they are not intended as a limitation on the scope thereof. Allparts and percentages in the examples are given on a weight basis unlessotherwise indicated.

Various terms used throughout the Examples have been abbreviated forconvenience. These are as follows:

2,6-DTBP 2,6-Di-tertiary-butylphenol CA Cyanuric acid HMT AHexamethylenetetraamine DMF N,N-dimethylformamide EXAMPLE I A reactorthoroughly purged with nitrogen was charged with 32.25 grams (0.25 mol)CA, 162.2 grams (0.5 mol) 2,6- DTBP, 24.8 grams (0.75 mol)paraformaldehyde and a solution of 200 mls DMF and 20 mls water. Thereactor and its contents were stirred and approximately 1 gram HMTAadded thereto. The reactor mixture was heated to about 1 12 C. for 5EXAMPLE I1 Employing a procedure similar to that described in Example I,tris( 3,5-di-t-butyl-4-hydroxybenzyl )isocyanurate was preparedemploying dimethyl sulfoxide as the reaction medium. The reactor wascharged with 32.25 grams CA, 154.5 grams 2,6 DTBP, 23.6 gramsparaformaldehyde, 200 mls. dimethyl sulfoxide, 20 mls water and 1 gramHMTA. The reaction mixture was heated for 21 hours. The recoveredproduct had a melt point of 220.5223 C. A 75% yield ofthetris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate was obtained.

EXAMPLE II! To a reactor containing 200 mls N-methyl pyrrolidone, l0 mlswater and 127.6 grams 2,6-DTBP was added 18.6 grams paraformaldehyde,25.8 grams CA and about 1 gram HMTA. The reaction mixture was heated forthree hours at a maximum temperature of 1 C. The reaction product had amelt point of 2l52l8 C. in the crude state. The yield of crude tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate was 80%.

EXAMPLE IV A pressure reactor thoroughly purged with nitrogen wascharged 256.8 grams 2,6-DTBP, 443 grams acetonitrile and 97.2 gramswater (18% water). Agitation was commenced at about 75 rpm with acontinuous nitrogen purge and 40.6 grams paraformaldehyde and 51.85grams CA charged to the reactor. After the addition of 1.65 grams HMTAcatalyst the nitrogen purge was terminated and the reactor sealed.Agitation was then increased and the reaction mixture heated to about115 C. The temperature was maintained for about 6 hours during whichtime the pressure within the reactor reached about 40 psig. The reactorwas then cooled to room temperature and the contents transferred onto afilter. After washing the material was dried and had a melt point in therange 216221 C. A 93.9% yield of tris(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate was obtained.

EXAMPLE V To demonstrate the ability of the present process to beconducted employing other basic catalysts a series of runs were madewherein different basic compounds were employed to catalyze the reactionas well as a run employing no catalyst. The procedure employed wassimilar to that described in Example l. The amounts of reactants,reaction conditions, and type and amount of catalyst are set forth belowin Table I. In all the runs, yields above about 50% were obtained. Evenwith no catalyst a 71% yieldtris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate was obtained. Allproducts were obtained in reasonably pure form after washing and/orrecrystal- EXAMPLE VI To demonstrate the ability to preparetris(3,5-di-t-butyl-4- hydroxybenzyl)isocyanurate by the base catalyzedreaction of the trimethylol derivative of CA with 2,6-DTBP, 12.9 grams(0.1 mol) CA, 200 mls DMF and 25 grams of 36% fonnalin solution (0.3 molformaldehyde) were charged to a reactor. The reaction mixture was heatedto C. for 2 hours and the trimethylol precursor formed. The resultingmethylol derivative had the formula and a portion was recovered as aglassy solid. 2,6-DTBP (63 grams; 0.31 mol) and about 1 gram tricaprylylmethyl ammonium hydroxide were then charged to the reactor and thereaction continued for approximately 10 hours. The crudetris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate was recovered as awhite crystalline solid melting at 207210 C. After purification theproduct was comparable in all respects to the isocyanurate obtained bythe previous procedures.

EXAMPLE VII CA was mono-substituted with a hindered phenol group byreacting 12.9 grams CA, 20.8 grams 2,6-DTBP and 3.5 gramsparaformaldehyde in 200 mls DMF containing 10 mls water in the presenceof HMT A catalyst. The reaction was conducted at about C. for 2 hours.The resulting 3,5-di-t-buty1-4- hydroxybenzyl isocyanurate, afterwashing with hexane and multiple recrystallization, had a sharp meltpoint.

EXAMPLE VIII CA substituted with two hindered phenol groups was preparedby reacting 3225 grams CA, 103 grams 2,6-DTBP and 15.8 gramsparaformaldehyde at about 1 12 C. Approximately 0.5 gram HMTA catalystwas employed and the reaction media was 10% aqueous DMF. Thebis(3,5-di-t-butyl-4- hydroxybenzyl) isocyanurate was recrystallizedfrom aqueous ethanol and melted between about 250258 C.

EXAMPLE 1X A mixed ester of CA was obtained by reacting hexylisocyanurate with 2,6-DTBP. 9.9 Grams hexyl isocyanurate (0.0465 mol),19.2 grams 2,6-DTBP (0.093 mol), and 2.8 grams paraformaldehyde (0.093mol) were reacted in about 100 mls 10% aqueous DMF with HMTA catalyst.The reaction was run for 7 hours between 1001 10 C. Recrystallizationfrom aqueous ethanol gave the mixed ester which melted at 110-1 16 C.

EXAMPLE X Following the procedure of Example V1 tris(3-methyl-5-tbutyl-4-hydroxybenzy1)isocyanurate was prepared. Thetrimethylol derivative of CA was first obtained by reacting 12.9 grams(0.1 mol) CA and 24.9 grams (0.3 mol) 36% formalin solution. Theresulting trimethylol derivative was then reacted in the presence ofHMTA catalyst with 61.5 grams (0.373 mol) 6-tbutyl-o-cresol. About 50grams of the tris(3- methyl-5-t-butyl-4-hydroxybenzyl)isocyanuratemelting lization. 65 between 148-150 C. was recovered.

TABLE 1 lm-nlurm- 1)Ml Reaction (A 2,6l)llll aldehyde water temp. Run(gr-mus) (grams) (grams) (1111s.) (:ttnlyst C.)

1 33.3 157.6 24.8 2110/20 None 112117 3.. 3;. 25 157.11 24. S 200/20Trihutylmninu (1 grum) 113 3 12.11 61.8 10 200/15 lotrumethylmmnoniumhydroxidv (1 gram) 115 4.. 154. 5 23.1; 200/'20 Sodium hydroxide (0.5gr'zrm) 113 5 154. 5 23.11 200/J0 lotnssium t-Iurtm'idv (1 1311111).100113 1L. 157.15 14.8 200F311 'lrivt hylvllwlizunirw ((1.5 gram). 115

Similarly, when 49.5 grams o-t-butyl-m-cresol was employed in the abovereaction tris(Z-methyl-St-butyl-4-hydroxybenzyl)isocyanurate wasobtained in good yield.

EXAMPLE Xl Thirty-two grams CA, 158 grams 2,6-di-sec-butyl phenol and24.8 grams paraformaldehyde were reacted in 220 ml aqueous DMF at about1 13 C. to give tris( 3,5-di-sec-butyl-4- hydroxybenzyl)isocyanurate.When 2,6-dimethyl phenol was substituted in the above reaction,approximately 57% yield tris(3,5-dimethyl-4-hydroxybenzyl isocyanuratemelting between 245252 C. was obtained. When a mixture of 2,6-di-t-butyl phenol and 2-t-butyl-o-cresol was employed, a mixed ester ofCA was obtained.

The hydroxybenzyl-substituted isocyanurates obtained by the presentprocess are useful stabilizers for a wide variety of organic materials.They are non-staining, possess low volatility and are extremelyeffective protective agents when incorporated in organic polymericmaterials. They are effective for the protection of both natural andsynthetic organic polymeric materials which are subject to oxidative,thermal and light-induced degradation. They are useful as stabilizersfor a-olefin homopolymers and copolymers and particularly useful withpolyethylene, polypropylene and ethylenepropylene copolymers andtel-polymers.

To demonstrate the effectiveness as stabilizers in a-olefin polymers,0.5 part tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate as preparedabove was dissolved in acetone and incorporated in 100 partshigh-density polyethylene by suspending the polyethylene in the acetonesolution and then removing the solvent with a rotary evaporator. Thestabilized polyethylene was hot milled at 290300 F. for 5 minutes andmolded into mil sheets at 300 F. The stabilized sample was subjected toan oxygen atmosphere at 140 C. and found to have an induction period ofabout 35 hours as compared to an unstabilized high-density polyethylenesample whose induction period was only 0.5 hour. When bis(3,5-di't-butyl-4- hydroxybenzyl)hexyl isocyanurate was similarlyincorporated in high-density polyethylene markedly increased stabilitywas obtained. For example, a polyethylene sample stabilized with 0.1part of the bis(3,5-di-t-butyl-4-hydroxybenzyl)hexyl isocyanurate had aninduction period of about 52 hours. When 0.2 partB-dilauryldithiodipropionate was employed with the bis-(3,5-di-t-butyl-4-hydroxybenzyl )hexyl isocyanurate the induction periodwas increased to 1 hours.

I claim:

1. A process for the preparation of hydroxybenzyl-substitutedisocyanurates which comprises heating together at a temperature fromabout 70 to 180 C. (l) a phenol or mixture of phenols having the formula1 14 I ia wherein R is an alkyl group containing from one to 18 carbonatoms and R R R and R are hydrogen or alkyl groups containing from oneto 18 carbon atoms, but at least one of the R R.,, R:, or R groups ishydrogen; and (2) an organic heterocyclic compound selected from thegroup consisting of cyanuric acid and partial esters of cyanuric acidhaving the formula wherein R is an alkyl radical containing from one to20 carbon atoms and R is hydrogen or an alkyl radical containing fromone to 20 carbon atoms and a formaldehyde-liberating compound in anorganic diluent having a solubility parameter above about 10 andcontaining up to about 40% by weight of water.

2. The process of claim 1 wherein the reaction is conducted in thepresence of an organic or inorganic basic compound as a catalyst.

3. The process of claim 2 wherein l is a 2,6-dialkyl phenol wherein Rand R are alkyl groups containing from one to 12 carbon atoms and R ishydrogen.

4. The process of claim 3 wherein the organic or inorganic basiccompound is selected from the group consisting of primary, secondary andtertiary monoamines, primary, secondary and tertiary polyamines, alkalimetal alcoholates, alkali metal hydroxides and quaternary ammoniumhydroxides and the reaction temperature is between about and C.

5. The process of claim 4 wherein 1) is a 2,6-di-t-alkyl phenol whereinR and R are tertiary alkyl groups containing from four to eight carbonatoms and R R and R are hydrogen.

6. The process of claim 5 wherein the formaldehyde-liberating compoundis selected from the group consisting of formalin, paraformaldehyde andtrioxane.

7. The process of claim 6 wherein the organic diluent is selected fromthe group consisting of amides, N-alkyl-substituted amides, dimethylsulfoxide, acetonitrile, propylene carbonate and N-methyl-Lpyrrolidone.

8. The process of claim wherein the organic heterocyclic compound iscyanuric acid, (1) is 2,6-di-t-butyl phenol, the formaldehyde-liberatingcompound is paraformaldehyde and the basic compound is a polyaminecontaining up to about 10 carbon atoms.

9. The process of claim 8 wherein the organic diluent is acetonitrilecontaining up to about 25% by weight water and the basic compound ishexamethylenetetraamine.

10. The process of claim 8 wherein the organic diluent isN,N-dimethylformamide containing up to about 25% by weight water and thebasic compound is hexamethylenetetraamine.

1]. The process of claim 6 wherein the organic heterocyclic compound isa partial ester of cyanuric acid wherein R is an alkyl group containingfrom six to 18 carbon atoms, l is 2,6- di-t-butyl phenol, theformaldehyde-liberating compound is paraformaldehyde and the basiccompound is a polyamine containing up to about 10 carbon atoms.

12. The process of claim 11 wherein the organic diluent contains up toabout 25% by weight water and is selected from the group consisting ofamides, N-alkyl-substituted amides, dimethyl sulfoxide, acetonitrile,propylene carbonate and N- methyl-Z-pyrrolidone and the basic compoundis hexamethylenetetraamine.

13. The process of claim 7 wherein the organic diluent contains up toabout 25% by weight water and is selected from the group consisting ofamides, N-alkyl-substituted amides, dimethyl sulfoxide, acetonitrile,propylene carbonate, and N- methyl-Z-pyrrolidone and the reactiontemperature is between about 90 and 150 C.

14. The process of claim 13 wherein the methylol derivative of cyanuricacid and 2,6-di-t-butyl phenol are employed.

15. The process of claim 14 wherein the basic compound is a polyaminecontaining up to about 10 carbon atoms.

16. The process of claim 13 wherein the methylol derivative of a partialester of cyanuric acid wherein R is an alkyl radical containing from sixto 18 carbon atoms and 2,6-di-t-butyl phenol are employed.

17. The process of claim 16 wherein the basic compound is a polyaminecontaining up to about 10 carbon atoms.

18. The process of claim 3 wherein the organic diluent is acetonitrilecontaining up to about 25% by weight water.

19. The process of claim 18 wherein l) is 2,6-di-t-butyl phenol, theorganic heterocyclic compound is cyanuric acid, theformaldehyde-liberating compound is paraformaldehyde and the basiccompound is hexamethylenetetraarnine.

20. The process of claim 18 wherein (1) is 2,6-di-t-butyl phenol, theorganic heterocyclic compound is a partial ester of cyanuric acidwherein R is an alkyl radical containing from six to 18 carbon atoms andR, is hydrogen, the formaldehydeliberating compound is paraformaldehydeand the basic compound is hexamethylenetetraamine.

2. The process of claim 1 wherein the reaction is conducted in thepresence of an organic or inorganic basic compound as a catalyst.
 3. Theprocess of claim 2 wherein (1) is a 2,6-dialkyl phenol wherein R2 and R3are alkyl groups containing from one to 12 carbon atoms and R6 ishydrogen.
 4. The process of claim 3 wherein the organic or inorganicbasic compound is selected from the group consisting of primary,secondary and tertiary monoamines, primary, secondary and tertiarypolyamines, alkali metal alcoholates, alkali metal hydroxides andquaternary ammonium hydroxides and the reaction temperature is betweenabout 90* and 150* C.
 5. ThE process of claim 4 wherein (1) is a2,6-di-t-alkyl phenol wherein R2 and R3 are tertiary alkyl groupscontaining from four to eight carbon atoms and R4, R5 and R6 arehydrogen.
 6. The process of claim 5 wherein the formaldehyde-liberatingcompound is selected from the group consisting of formalin,paraformaldehyde and trioxane.
 7. The process of claim 6 wherein theorganic diluent is selected from the group consisting of amides,N-alkyl-substituted amides, dimethyl sulfoxide, acetonitrile, propylenecarbonate and N-methyl-2-pyrrolidone.
 8. The process of claim 7 whereinthe organic heterocyclic compound is cyanuric acid, (1) is2,6-di-t-butyl phenol, the formaldehyde-liberating compound isparaformaldehyde and the basic compound is a polyamine containing up toabout 10 carbon atoms.
 9. The process of claim 8 wherein the organicdiluent is acetonitrile containing up to about 25% by weight water andthe basic compound is hexamethylenetetraamine.
 10. The process of claim8 wherein the organic diluent is N,N-dimethylformamide containing up toabout 25% by weight water and the basic compound ishexamethylenetetraamine.
 11. The process of claim 6 wherein the organicheterocyclic compound is a partial ester of cyanuric acid wherein R isan alkyl group containing from six to 18 carbon atoms, (1) is2,6-di-t-butyl phenol, the formaldehyde-liberating compound isparaformaldehyde and the basic compound is a polyamine containing up toabout 10 carbon atoms.
 12. The process of claim 11 wherein the organicdiluent contains up to about 25% by weight water and is selected fromthe group consisting of amides, N-alkyl-substituted amides, dimethylsulfoxide, acetonitrile, propylene carbonate and N-methyl-2-pyrrolidoneand the basic compound is hexamethylenetetraamine.
 13. The process ofclaim 7 wherein the organic diluent contains up to about 25% by weightwater and is selected from the group consisting of amides,N-alkyl-substituted amides, dimethyl sulfoxide, acetonitrile, propylenecarbonate, and N-methyl-2-pyrrolidone and the reaction temperature isbetween about 90* and 150* C.
 14. The process of claim 13 wherein themethylol derivative of cyanuric acid and 2,6-di-t-butyl phenol areemployed.
 15. The process of claim 14 wherein the basic compound is apolyamine containing up to about 10 carbon atoms.
 16. The process ofclaim 13 wherein the methylol derivative of a partial ester of cyanuricacid wherein R is an alkyl radical containing from six to 18 carbonatoms and 2,6-di-t-butyl phenol are employed.
 17. The process of claim16 wherein the basic compound is a polyamine containing up to about 10carbon atoms.
 18. The process of claim 3 wherein the organic diluent isacetonitrile containing up to about 25% by weight water.
 19. The processof claim 18 wherein (1) is 2,6-di-t-butyl phenol, the organicheterocyclic compound is cyanuric acid, the formaldehyde-liberatingcompound is paraformaldehyde and the basic compound ishexamethylenetetraamine.
 20. The process of claim 18 wherein (1) is2,6-di-t-butyl phenol, the organic heterocyclic compound is a partialester of cyanuric acid wherein R is an alkyl radical containing from sixto 18 carbon atoms and R1 is hydrogen, the formaldehyde-liberatingcompound is paraformaldehyde and the basic compound ishexamethylenetetraamine.